[9.x] Add keyBy() method to Arr helpers (#41029)

* Add index() method to Arr helpers

* fix data value

* fix spaces

* fix styleci

* change method name index to keyBy

* formatting

Co-authored-by: Taylor Otwell <taylor@laravel.com>

src/Illuminate/Collections/Arr.php

@@ -423,6 +423,18 @@ public static function isList($array)
         return ! self::isAssoc($array);
     }
 
+    /**
+     * Key an associative array by a field or using a callback.
+     *
+     * @param  array  $array
+     * @param  callable|array|string
+     * @return array
+     */
+    public static function keyBy($array, $keyBy)
+    {
+        return Collection::make($array)->keyBy($keyBy)->all();
+    }
+
     /**
      * Get a subset of the items from the given array.
      *

tests/Support/SupportArrTest.php

@@ -1021,4 +1021,19 @@ function ($a, $b) {
             ['name' => 'John', 'age' => 8,  'meta' => ['key' => 3]],
         ], $sortedWithCallable);
     }
+
+    public function testKeyBy()
+    {
+        $array = [
+            ['id' => '123', 'data' => 'abc'],
+            ['id' => '345', 'data' => 'def'],
+            ['id' => '498', 'data' => 'hgi'],
+        ];
+
+        $this->assertEquals([
+            '123' => ['id' => '123', 'data' => 'abc'],
+            '345' => ['id' => '345', 'data' => 'def'],
+            '498' => ['id' => '498', 'data' => 'hgi'],
+        ], Arr::keyBy($array, 'id'));
+    }
 }